Stereochemistry of Carbenic 1,2-Vinyl Shifts
J . Org. Chem., Vol. 63, No. 4, 1998 1183
were observed. The products were identified by comparison
with samples from appropriate syntheses. The preparation
of 1-phenyl-2,2,exo-4-trimethylbicyclo[1.1.0]butane (35) [1H
NMR (CDCl3) δ 0.88 (d, J ) 6 Hz, 3 H), 0.90 (s, 3 H), 0.95 (s,
3 H), 1.6 (br s, 1 H), 1.9 (br q, J ) 6 Hz, 1 H), 7.15-7.25 (m,
5 H)] has been reported.26 For the remaining products, see
below.
methylindene (57, 56%) have been reported.22 Analogous
treatment of (Z)-55 gave a similar product mixture; (Z)-36 was
not obtained.
4,4-Dim et h yl-5-p h en yl-2-p en t en e (31). Following a
method similar to the preparation of 54, the ylide derived from
ethyltriphenylphosphonium iodide (2.5 g, 6.2 mmol) and NaH
(60%, 0.25 g, 62 mmol) in DMSO (5 mL) reacted with
2,2-dimethyl-3-phenylpropanal27 (0.5 g, 3.1 mmol) to give 0.4
g (80%) of crude 31, E:Z ) 3:7. The mixture was separated
by PGC (3 m Apiezon, 150 °C). E-31: 1H NMR (CDCl3) δ 0.95
(s, 6 H), 1.65 (dd, J ) 6.5, 1.5 Hz, 3 H), 2.55 (s, 2 H), 5.2 (dq,
J ) 16, 6.5 Hz, 1 H), 5.45 (dq, J ) 16, 1.5 Hz, 1 H), 7.05-7.25
(m, 5 H). Z-31: 1H NMR (CDCl3) δ 1.1 (s, 6 H), 1.62 (dd, J )
7, 1.5 Hz, 3 H), 2.65 (s, 2 H), 5.2 (dq, J ) 12, 7 Hz, 1 H), 5.45
(dq, J ) 12, 1.5 Hz, 1 H), 7.1-7.25 (m, 5 H). Anal. Calcd for
To a stirred, nitrogen-blanketed solution of 1-bromo-2-
methyl-1-phenylpropene (58)28 (4.0 g, 19 mmol) in ether (20
mL) was added at -78 °C n-butyllithium (1.6 M in ether, 40
mL, 64 mmol). After the mixture was allowed to warm to room
temperature, stirring was continued for 5 h. A solution of
N-formylpiperidine (2.5 g, 22 mmol) in ether (10 mL) was then
added, and the reaction was allowed to proceed for 2 h at room
temperature. The mixture was poured into ice water, and the
phases were separated. The aqueous phase was extracted with
ether (50 mL). The combined ether solutions were dried
(MgSO4) and concentrated in vacuo. Chromatography (silica
gel, ether-hexane ) 1:1) of the residue afforded 0.22 g (6.2%)
of 2-methyl-3-phenyl-2-heptene (59): [1H NMR (CDCl3) δ 0.8-
1.4 (m, 7 H), 1.6 (s, 3 H), 1.8 (s, 3 H), 2.3 (t, J ) 6 Hz, 2 H),
7.0-7.4 (m, 5 H)] and 1.98 g (65%) of 3-methyl-2-phenyl-2-
C
13H18: C, 89.59; H, 10.41. Found: C, 89.48; H, 10.33.
4,4-Dim eth yl-5-m eth oxy-5-p h en yl-(E)-2-p en ten e (E-34).
To a stirred, refluxing solution of E-28 (0.6 g, 3.2 mmol) in
methanol (5 mL) was added NaBH4 (0.25 g, 6.6 mmol). After
cooling to room temperature over 4 h, the mixture was
partitioned between water and pentane. The combined pen-
tane solutions were dried (MgSO4) and concentrated in vacuo.
GC indicated a 1:1 mixture of ketone and alcohol which was
separated by HPLC (Si-60-5, ether-hexane ) 1:1). 2,2-Di-
methyl-1-phenyl-(E)-3-penten-1-ol: 1H NMR (CDCl3) δ 0.9 (s,
3 H), 0.95 (s, 3 H), 1.7 (br d, J ) 7 Hz, 3 H), 4.4 (m, 1 H),
5.3-5.6 (m, 2 H), 7.3 (br s, 5 H). Anal. Calcd for C13H18O: C,
82.06; H, 9.53. Found: C, 82.05; H, 9.52.
1
butenal (60) [IR (CDCl3) 1670 cm-1 (CdO); H NMR (CDCl3)
δ 1.8 (s, 3 H), 2.35 (s, 3 H), 6.9-7.1 (m, 2 H), 7.3-7.4 (m, 3 H),
10.25 (s, 1 H)].
Following the procedure described for 15, 2,2-dimethyl-1-
phenyl-(E)-3-penten-1-ol (0.19 g, 1.0 mmol) was treated with
NaH (50 mg, 2.1 mmol) and methyl iodide (0.6 g, 4 mmol) to
give 0.19 g (93%) of 34: 1H NMR (CDCl3) δ 0.9 (s, 3 H), 0.95
(s, 3 H), 1.65 (d, J ) 6 Hz, 3 H), 3.15 (s, 3 H), 3.8 (s, 1 H),
5.0-5.7 (m, 2 H), 7.1-7.35 (m, 5 H). Anal. Calcd for
To a suspension of sodium amide (0.25 g, 6.2 mmol) in ether
(20 mL) was added ethyltriphenylphosphonium iodide (2.5 g,
6.2 mmol). The mixture was heated at reflux for 24 h.
A
C
14H20O: C, 82.30; H, 9.87. Found: C, 82.38; H, 9.80.
solution of 60 (0.5 g, 3.1 mmol) in ether (5 mL) was then added,
and heating at reflux was continued for 2 h. The solution was
filtered and concentrated in vacuo to give 0.4 g (75%) of 36,
E:Z ) 1:4. The mixture was purified by PGC (1 m DC200,
140 °C), which did not separate the isomers. Z-36: 1H NMR
(CDCl3) δ 1.4 (dd, J ) 7, 1.5 Hz, 3 H), 1.5 (s, 3 H), 1.7 (s, 3 H),
5.5 (dq, J ) 11, 7 Hz, 1 H), 6.1 (dq, J ) 11, 1.5 Hz, 1 H), 7.0-
7.35 (m, 5 H). Anal. Calcd for C13H16: C, 90.64; H, 9.36.
Found: C, 90.44; H, 9.24.
2-Meth yl-3-p h en yl-2,4-h exa d ien e (36). To a solution of
1-propenylmagnesium bromide, prepared from magnesium (3.7
g, 0.12 mol) and 1-bromopropene (18.1 g, 0.15 mol) in THF
(160 mL), was added a solution of isobutyrophenone (18.0 g,
0.12 mol) in THF (30 mL). The mixture was heated at reflux
for 2 h. Conventional workup afforded 18.0 g (79%) of
2-methyl-3-phenyl-4-hexen-3-ol (55) whose E,Z isomers (1:3,
GC) were separated by chromatography (silica gel, hexane-
ether ) 4:1). Z-55: 1H NMR (CDCl3) δ 0.8 (d, J ) 7 Hz, 3 H),
0.95 (d, J ) 7 Hz, 3 H), 1.6 (dd, J ) 7, 1 Hz, 3 H), 2.1 (sept, J
) 7 Hz, 1 H), 5.65 (dq, J ) 11, 7 Hz, 1 H), 6.0 (dq, J ) 11, 1
Hz, 1 H), 7.1-7.55 (m, 5 H). E-55: 1H NMR (CDCl3) δ 0.75
(d, J ) 7 Hz, 3 H), 0.9 (d, J ) 7 Hz, 3 H), 1.75 (dd, J ) 7, 1 Hz,
3 H), 2.15 (sept, J ) 7 Hz, 1 H), 5.3-6.1 (m, 2 H), 7.1-7.55
(m, 5 H). Anal. Calcd for C13H18O: C, 82.06; H, 9.53.
Found: C, 82.01; H, 9.53.
To (E)-55 (3.0 g, 15.8 mmol) was added 0.5 g of 85%
phosphoric acid. After the mixture was heated at 80 °C for 2
h, it was partitioned between pentane and water. The pentane
solutions were dried (MgSO4) and concentrated to give 2.0 g
(74%) of a product mixture which was separated by PGC (2.5
m Apiezon, 160 °C). 5-Methyl-4-phenyl-1,3-hexadiene (56,
18%): 1H NMR (CDCl3) δ 1.05 (d, J ) 7 Hz, 6 H), 2.7 (sept, J
) 7 Hz, 1 H), 4.8-5.3 (m, 2 H), 5.95-6.3 (m, 2 H), 7.0-7.5 (m,
5 H). 2-Methyl-3-phenyl-2,4(E)-hexadiene (E-36, 26%): 1H
NMR (CDCl3) δ 1.55 (s, 3 H), 1.7 (dd, J ) 7, 1 Hz, 3 H), 1.95
(s, 3 H), 5.0 (dq, J ) 16, 7 Hz, 1 H), 6.65 (dq, J ) 16, 1 Hz, 1
H), 7.0-7.5 (m, 5 H). Anal. Calcd for C13H16: C, 90.64; H,
9.36. Found: C, 90.53; H, 9.43. Data for 3-isopropyl-1-
1-Meth yl-2-p h en yl-1-(1-p r op en yl)cyclop r op a n es (37).
Using the same procedure for the synthesis of trans-1-methyl-
2-phenylcyclopropanemethanol (trans-50),24 ethyl cis-1-methyl-
2-phenylcyclopropanecarboxylate24b was reduced to give 90%
of cis-50: 1H NMR (CDCl3) δ 0.7-1.2 (m, 2 H), 1.35 (s, 3 H),
2.05 (dd, J ) 9, 7 Hz, 1 H), 3.25 (m, 2 H), 7.1-7.3 (m, 5 H).
Following a method similar to the preparation of 53, oxidation
of the alcohols with MnO2 (benzene, reflux) afforded the
corresponding aldehydes (91-95%). trans-1-Methyl-2-phenyl-
cyclopropanecarboxaldehyde (trans-51): IR (CDCl3) 1690 cm-1
(CdO), 1H NMR (CDCl3) δ 0.95 (s, 3 H), 1.4-1.7 (m, 2 H), 2.55
(dd, J ) 9, 7 Hz, 1 H), 7.1-7.3 (m, 5 H), 8.95 (s, 1 H). cis-1-
Methyl-2-phenylcyclopropanecarboxaldehyde (cis-51):29: IR
1
(CDCl3) 1690 cm-1 (CdO); H NMR (CDCl3) δ 1.35 (s, 3 H),
1.4-1.7 (m, 2 H), 2.55 (dd, J ) 9, 7 Hz, 1 H), 7.1-7.3 (m, 5 H),
8.55 (s, 1 H). Wittig reaction of trans-51 with ethyltriphen-
ylphosphonium iodide-NaH-DMSO (see preparation of 54)
afforded predominantly (E:Z ) 1.8, 75%) trans-1-methyl-2-
1
phenyl-1-[(E)-1-propenyl]cyclopropane (trans-E-37); H NMR
(CDCl3) δ 0.95 (s, 3 H), 1.1 (d, J ) 7 Hz, 2 H), 1.85 (d, J ) 5
Hz, 3 H), 2.1 (t, J ) 7 Hz, 1 H), 5.0-5.8 (m, 2 H), 7.1-7.4 (m,
5 H). The Wittig reaction of trans-51 with ethyltriphenylphos-
phonium iodide-NaNH2-ether (see preparation of Z-36) gave
predominantly (E:Z ) 0.2, 83%) trans-1-methyl-2-phenyl-1-
[(Z)-1-propenyl]cyclopropane (trans-Z-37); 1H NMR (CDCl3) δ
0.9 (s, 3 H), 1.0 (dd, J ) 6.5, 3.5 Hz, 1 H), 1.05 (dd, J ) 8.5,
3.5 Hz, 1 H), 1.8 (dd, J ) 7, 1.5 Hz, 3 H), 2.1 (dd, J ) 8.5, 6.5
(27) (a) Artaud, I.; Torossian, G.; Viout, P. Tetrahedron 1985, 41,
5031. (b) Stork, G.; Dowd, S. R. Org. Synth. 1988, Collect. Vol. VI,
526.
(28) Knorr, R.; Lattke, E. Chem. Ber. 1981, 114, 2116.
(29) (a) Scribe, P.; Monot, R. M.; Wiemann, J . Tetrahedron Lett.
1967, 5157. (b) Scribe, P.; Wiemann, J . Bull. Soc. Chim. Fr. 1971, 2268.